An acoustic sensor is often employed on a downhole tool to measure properties of a subterranean formation. For example, the acoustic sensor may be used to determine formation compressional slowness, Stonely slowness, and/or other properties. Generally, a transmitter generates an acoustic signal that propagates toward the subterranean formation. The signal is refracted by the subterranean formation toward a receiver of the acoustic sensor, which receives the signal. The signal may then be processed to determine the properties of the subterranean formation.